 Research
 Open Access
Advanced configuration of hybrid passive filter for reactive power and harmonic compensation
 O. Fatih Kececioglu^{1},
 Hakan Acikgoz^{2} and
 Mustafa Sekkeli^{1}Email author
Received: 29 December 2015
Accepted: 26 July 2016
Published: 2 August 2016
Abstract
Harmonics is one of the major power quality problems for power systems. The harmonics can be eliminated by power filters such as passive, active, and hybrid. In this study, a new passive filter configuration has been improved in addition to the existing passive filter configurations. Conventional hybrid passive filters are not successful to compensate rapidly changing reactive power demand. The proposed configure are capable of compensating both harmonics and reactive power at the same time. Simulation results show that performance of reactive power and harmonic compensation with advanced hybrid passive filter is better than conventional hybrid passive filters.
Keywords
 Hybrid passive filters
 Harmonics
 Power quality
 Reactive power compensation
Background
In the latest years, harmonic distortion has become one of the most significant power quality problems. The primary causes of this problem can be sorted as soft starters, rectifiers and increase of devices that of semiconductor circuits. Nonlinear loads cause harmonic distortion within the voltage and current waveform in the power system. Harmonics result in numerous problems such as low power factor and overheat on the power systems, electrical devices and transformers (Lee and Wu 1998; Snal et al. 2004; Hamadi et al. 2010; Sekkeli and Tarkan 2013). In order to protect other users in power system from the effects of the harmonics caused by nonlinear devices, the IEEE 5191992 standard has imposed specific limits on levels of voltage and current harmonics. Mainly, it sets limits of harmonic current and voltage at the point of common coupling.
Harmonic distortion has been suppressed by passive filters, active filters, and hybrid filters. Among these, the passive filters have been widely applied in filtering harmonics in power systems up to the present since it has high reliability, efficiency, low cost and a simple configuration. Also, passive filters are preferred where harmonics and reactive power compensation have been desired. Many different topologies of passive filters have been suggested in the literature, and the parallel filter configuration is most preferred filter topologies (Thirumoorthi and Yadaiah 2015; Zobaa 2005; Singh and Verma 2007; Cheng et al. 1996).
Parallel passive filters are more suitable for compensating current source nonlinear loads. On the other hand, it has been shown that the parallel passive filter is suitable for compensating current source type of nonlinear loads. The series passive filter can be used to compensate for voltage source type of nonlinear loads. Hybrid passive filter (HPF) which consist of a serial passive filter and parallel passive filter can be used for all type of nonlinear loads. The HPF delivers harmonic and reactive power compensation and is also insensitive to source impedance (Prasad and Sudhakar 2014; Dzhankhotov and Pyrhonen 2013; Jou et al. 2001).
Despite the fact that HPF is considerable performed to harmonic mitigation, this filter cannot be fully successful to compensate the reactive power for suddenly changing nonlinear loads.
In the study by Rahmani et al. proposed a new single phase hybrid passive filter (SPHPF) for compensating load voltage and current harmonics, correct power factor. Additionally, the SPHPF eliminate the chances of series and parallel resonance and eliminates large variation of power factor and terminal voltage with varying loads under stiff and distorted source conditions (Rahmani et al. 2008).
Singh et al. focused on new hybrid passive filter topology, which provides harmonic compensation at par with active filters, whose design is insensitive to source impedance, eliminate the chances of resonance over wide spectra and reduces large variation of power factor and terminal voltage with varying rectifier load (Singh et al. 2005).
In the study by Hsan et al. proposed a shunt hybrid power filter (SHPF) which consists of a smallrated active power filter in series with a fifthtuned passive filter. Since the latter takes care of the major burden of compensation, the rating of the shunt hybrid power filter is much smaller than that in the conventional shunt active power filter (Hsan et al. 2013).
Hamadi et al. proposed a novel topology for a three phase hybrid passive filter (HPF) to compensate for reactive power and harmonics. The proposed HPF configuration has many features such as: insensitivity to sourceimpedance variations; no series or parallel resonance problems; fast dynamic response. According to experimental and simulation results show that the proposed HPF configuration provides compensate all voltage and current harmonics and reactive power for large nonlinear loads (Hamadi et al. 2010).
Few researchers have investigated the hybrid passive filter configuration in order to compensate for reactive power and harmonics (Hamadi et al. 2010; Rahmani et al. 2007). The performance of the hybrid passive filter has been investigated for any load types such as rectifiers and motor drivers. Despite that, the nonlinear loads are acceptable for harmonics mitigation performance of the filters, these loads are not suitable for reactive power compensation performance. Since reactive power demand of the loads has been minimized. In order to analysis of reactive power compensation performance of filter should be used varying loads or suddenly switched on/off loads.
This paper proposes a new configuration of hybrid passive power filter in order to overcome the abovementioned harmonic standard. The advanced hybrid passive filter (AHPF) configuration is composed of two thyristor controlled parallel passive filters (TCPF) and a serial passive filter (SPF). The AHPF is designed to rapidly changing nonlinear loads in order to reactive power compensation. The TCPF is capable both reactive power compensation and current harmonics mitigation of nonlinear loads.
This paper is arranged as follows: “Hybrid passive filters” section briefly presents theory of hybrid passive filter. “Advanced hybrid passive filter configuration” section presents details of advanced hybrid passive power filter. Simulation studies and results of AHPF shows in “Simulation results” section. “Conclusion” section delivers our conclusions and a brief discourse on future research directions.
Hybrid passive filters
The SPF is presented a low impedance at the fundamental frequency thus absorbing the voltage harmonics of interest. While SPF blocks for voltage fed type of harmonics, the TCPF eliminates to current fed type harmonics. Therefore, HPF is able to compensate to all type of harmonics caused by nonlinear loads (Rahmani et al. 2007).
Series passive filter
Figure 2b illustrate that the SPF offers high impedance to all higher harmonic frequencies. Concurrently, SPF presents very low impedance at the fundamental frequency. This is significant because notable impedance at the network frequency may lead to considerable voltage drop.
Thyristor controlled passive filter
Advanced hybrid passive filter configuration
Comparison of the HPF and AHPF
Comparison criterions  HPF  AHPF 

Voltage fed type harmonics compensating  Capable  Accuracy 
Current fed type harmonics compensating  Capable  Accuracy 
Reactive power compensating  Limited  Accuracy 
Operating modes of the AHPF
Operating mode  TCPF 1  TCPF 2 

Normal operating  –  – 
Power factor improver  Compensator  Compensator 
Power factor and power quality improver  Compensator  Filter 
Power quality improver  Filter  Filter 

One of them is total harmonic distortion level of current (THD _{ I }) at the load side.

Another one is the ratio of reactive power and active power.
If distortion level (THD _{ I }) at load side is smaller than 5 % and ratio of power parameters is smaller than 20 %, the AHPF is operated without compensator and filter. This operating mode is normal operating mode of AHPF. If distortion level (THD _{ I }) at load side is smaller than 5 % and the ratio of power parameters is greater than 20 %, the AHPF is operated as reactive power compensator. If distortion level (THD _{ I }) at load side is greater than 5 % and ratio of power parameters is smaller than 20 %, the AHPF is operated as harmonic filter. If distortion level (THD _{ I }) at load side is greater than 5 % and ratio of power parameters is greater than 20 %, the AHPF is operated as both harmonic filter and reactive power compensator at the same time.
Simulation results
Power system parameters
Line voltage  V _{ p–p }  400 V 
Line frequency  f  50 Hz 
Line impedance  L _{ s }  0.5 mH 
R _{ s }  0.1 Ω  
Simulation step time  T _{ s }  5 µs 
Calculated values of new filter topology
SPF capacitor  C _{ SF }  299 µF 
SPF reactor  L _{ SF }  33.67 mH 
TCPF capacitor  C _{ PF }  90 µF 
TCPF reactor  L _{ PF }  113 mH 
Loads modelling
Parameters of load models
Fixed nonlinear load  R _{ L }  100 Ω 
L _{ L }  25 mH  
Switched nonlinear load  R _{ SL }  200 Ω 
Fixed load  P _{ FL }  500 W 
Q _{ FL }  1500 VAr  
Load 1  P _{1}  100 W 
Q _{1}  1000 VAr 
Control system of TCPFs
Comparison of conventional HPF and AHPF
In this part of simulation studies, proposed AHPF configuration is compared to conventional HPF. The effect of proposed configuration on the simulated power system is examined for reactive power compensation and harmonic mitigation. Although HPF has only filter mode, the AHPF has three different operating modes. While HPF is only operated power quality improver, AHPF is operated both power factor and power quality improver in this simulation studies.
As shown in Fig. 11, total harmonic distortion levels of voltage (THD _{ V }) and current (THD _{ I }) is 0.05 and 4.17 %, respectively. THD level of current (THD _{ I }) is smaller than specific limit that is mentioned IEEE 5191992 standard. As a result, conventional HPF configuration is successful in compensating voltage and current types of harmonics at load side.
As shown in Fig. 12, THD level of PCC voltage (THD _{ V }) is nearly close to 0.00 and THD level of PCC current (THD _{ I }) is 2.34 %. As clearly seen in this Fig. 13, the voltage and current waveforms at the PCC become close to a sinusoidal form after using by AHPF. It is explicitly illustrated from Figs. 12 and 13 that proposed filter configuration almost completely eliminate the harmonics caused by nonlinear load. As shown in Fig. 13, due to AHPF is capable of working reactive power compensation mode, current of loads at the PCC is decreased compared to unfiltered conditions. Consequently, it is observed that AHPF is more precise than HPF.
After the switched on load 1, it is observed that reactive power of loads groups has increased from 945 to 1276 VAr. As clearly seen in Fig. 14, reactive power compensation performance of HPF is limited and fixed. Capacitive reactive power of the HPF is 483 VAr. Before switched on load 1, power factor value at PCC side is 0.79. After switched on load 1, it is shown that power factor has decreased. Reactive power at the PCC side has increased from 462 to 793 VAr. Performance of HPF configuration is not satisfactory for reactive power compensation.
Scenario 1: Switching load 1
Scenario 2: Switching nonlinear load
Conclusion
In this paper, a new hybrid passive filter that is named AHPF is developed in order to both harmonic mitigation and reactive power compensation. Reactive power and harmonic compensation performance of AHPF compared to conventional HPF. Many simulation studies have been performed for this purpose. The mainly advantage of proposed filter, while HPF provides limited capacitive reactive power, AHPF provides precise capacitive reactive power for power factor improvement. Whole simulation studies show that, THD levels of current and voltage at the PCC side are acceptable for the power quality standards. Additionally, simulation results indicate that power factor of the system is fixed about 1.0 for all simulation conditions. As a result of this studies, performance of AHPF configuration is more accuracy in order to reactive power compensation and harmonics mitigation as compared to conventional HPF.
Abbreviations
AHPF: advanced hybrid passive filter; HPF: hybrid passive filter; TCPF: thyristor controlled parallel passive filter; SPF: series passive filter; THD: total harmonic distortion; PCC: point of common coupling.
List of symbols
 Z :

impedance
 L :

inductor
 C :

capacitor
 V :

voltage
 Q :

reactive power
 P :

active power
 f :

frequency
 T :

time
 R :

resistor
 K :

gain
Subscripts
 S :

source
 SF :

series passive filter
 PF :

parallel passive filter
 L :

load
 I :

current
 v :

voltage
 p–p :

phase–phase
 SL :

switched load
Declarations
Authors’ contributions
MS provide the basic idea of the research and supervise. FK researched the background literature and developed the Simulink/MATLAB model of the advanced hybrid passive filter configuration. HA improved existing simulation studies and commented the comparison of conventional HPF and AHPF results. FK and HA organized and drafting of the manuscript. All authors read and approved the final manuscript.
Acknowledgements
The authors would like to thank the editors and referees for giving useful suggestions for improving the work.
Competing interests
The authors declare that they have no competing interests.
Funding
This work was financially supported by the Kahramanmaras Sutcu Imam University, Scientific Research Projects Unit, the project entitled “Advanced Hybrid Passive Filter Design Based on TCR for Reactive Power and Harmonic Compensation and Real Time Power Quality Monitoring Automation” under Project No: 2014/238M.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Authors’ Affiliations
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